Calcium binding peptides

Abstract

Disclosed herein are a class of compounds comprising peptides of the sequence (X-Y-Z) n , wherein X is an amino acid selected from aspartic acid, glutamic acid, asparagine, alanine and glutamine, and Y and Z are amino acids selected from alanine, serine, threonine, phosphoserine, phosphothreonine, and their derivatives. These compounds have the property of binding tightly and specifically to calcified surfaces, making them useful for a variety of applications including remineralization of tooth and bone surfaces, diagnosis of bone and tooth defects, treatment of bone and tooth defects, and analysis of the presence and location of calcified deposits both in vitro and in vivo and in industrial, synthetic, medical, dental, and research applications where identification, localization, or manipulation of calcification is desirable.

1 . A peptide comprising one or more calcium binding domains, wherein said calcium binding domains each comprise the sequence (X-Y-Z) n , wherein X is an amino acid selected from the group consisting of aspartic acid, glutamic acid, asparagine, alanine and glutamine, Y and Z are amino acids independently selected from the group consisting of alanine, serine, threonine, phosphoserine, and phosphothreonine, n is a number from 1 to 40, said peptide ranges in length from three to about 120 amino acids, and wherein said peptide binds to one or more moieties selected from the group consisting of calcium phosphate, hydroxyapatite, demineralized bone, demineralized tooth, arterial plaque, sesamoids, calcium minerals, bone, dentin, enamel, and calcium oxalate. 
     
     
         2 . The peptide of  claim 1 , wherein said peptide has a length of about 3 to about 100 amino acids. 
     
     
         3 . The peptide of  claim 1 , wherein n is a number from 2 to 8. 
     
     
         4 . The peptide of  claim 1 , wherein X is aspartic acid (SEQ ID NO:38). 
     
     
         5 . The peptide of  claim 4 , wherein Y and Z are serine (SEQ ID NO:39). 
     
     
         6 . The peptide of  claim 5 , wherein the amino acid sequence of said peptide is Asp Ser Ser Asp Ser Ser (SEQ ID NO:12). 
     
     
         7 . The peptide of  claim 5 , wherein the amino acid sequence of said peptide is (Asp Ser Ser) 4  (SEQ ID NO:13). 
     
     
         8 . The peptide of  claim 5 , wherein the amino acid sequence of said peptide is (Asp Ser Ser) 6  (SEQ ID NO:14). 
     
     
         9 . The peptide of  claim 5 , wherein the amino acid sequence of said peptide is (Asp Ser Ser) 8  (SEQ ID NO:15). 
     
     
         10 . (canceled) 
     
     
         11 . The composition of  claim 27 , wherein said peptide is attached to a detectable label and said detectable label comprises a moiety selected from the group consisting of a fluorophore, a chromophore, an affinity tag, an antigen tag, a radioactive label, and a spin label. 
     
     
         12 . (canceled) 
     
     
         13 . The composition of  claim 27 , wherein said peptide is attached to one or moieties selected from the group consisting of an anticancer compound, and an antimicrobial compound. 
     
     
         14 . The composition of  claim 27 , wherein said peptide is attached to an antimicrobial peptide. 
     
     
         15 . The composition of  claim 14 , wherein said antimicrobial peptide is linked to said peptide via an amino acid linker sequence. 
     
     
         16 . A method of mitigating a tooth defect characterized by tooth demineralization in a subject, comprising administering the peptide of  claim 1  to said subject, wherein said administration results in tooth remineralization. 
     
     
         17 . A method of treating a bone defect characterized by decreased bone density in a subject, comprising administering the peptide of  claim 1  to said subject, wherein said administration results in an increase in bone density. 
     
     
         18 . A method of identifying a tooth defect characterized by tooth demineralization in a subject, said method comprising:
 administering to said subject a composition comprising a peptide according to  claim 1  attached to a detectable label, whereby said peptide preferentially binds a demineralized tooth surface; and   detecting said detectable label, thereby indicating the location of said tooth defect.   
     
     
         19 . A method of identifying a bone defect characterized by bone demineralization in a subject, said method comprising:
 administering to said subject a composition comprising a peptide according to  claim 1  attached to a detectable label, whereby said peptide preferentially binds a demineralized bone surface; and   detecting said detectable label, thereby indicating the location of said bone defect.   
     
     
         20 . A kit comprising the peptide of  claim 1 . 
     
     
         21 . The peptide of  claim 1 , wherein said peptide is not phosphorylated. 
     
     
         22 . The peptide of  claim 1 , wherein one or more residues comprising said peptide are phosphorylated. 
     
     
         23 . The peptide of  claim 1 , wherein said peptide has a binding affinity (KA) for hydroxyapatite of greater than 15,000 M −1 . 
     
     
         24 . The peptide of  claim 1 , wherein said peptide has a binding affinity (KA) for hydroxyapatite of greater than 50,000 M −1 . 
     
     
         25 . A method of inhibiting bacterial growth on a calcified surface in a subject, said method comprising
 administering to said subject a composition comprising the peptide according to  claim 1  attached to an antimicrobial peptide, whereby said peptide preferentially binds a calcified surface and said antimicrobial peptide inhibits bacterial growth on said surface.   
     
     
         26 . A method of reducing tooth sensitivity in a subject, said method comprising
 administering to said subject a composition comprising the peptide according to  claim 1  in an amount sufficient to reduce tooth sensitivity in said subject.   
     
     
         27 . A composition comprising a peptide according to any of  claims 1 - 9  and  21 - 24 , wherein said peptide is attached to a moiety selected from the group consisting of a detectable label, an anti-cancer compound, and an antimicrobial compound.